Many semiconductor devices are designed to be implemented outdoors or in similar uncontrolled and potentially harsh environments. For example, photovoltaic cells must be mounted where the amounts of sunlight reaching the cells tends to be maximized. The typical outdoor mounting of photovoltaic cells and similar semiconductor apparatus necessarily exposes these devices to rain, snow, dew, or other harsh and wet environments. The operative layers and surfaces of many semiconductor devices such as photovoltaic cells may be degraded through contact with water, water vapor or other substances potentially present in the installation environment. Accordingly, devices such as photovoltaic cells are typically encapsulated or packaged in some type of moisture barrier structure or protective material.
Devices subjected to moist environments may be placed in a separate weather proof enclosure, possibly having relatively impermeable glass windows. Alternatively a device may be potted in a heavy and weather resistant material such as an epoxy resin, should the opacity of certain potting materials not prove problematic. Glass weather barriers and similar materials, however, are relatively heavy, inflexible, prone to breakage and difficult to handle or install. Therefore, technologies have been developed for associating a relatively thin and flexible moisture barrier with the exterior and or interior surfaces of a semiconductor device such as a photovoltaic cell. A thin film moisture barrier may be deposited directly onto the device in one or more manufacturing steps. Alternatively, a free standing thin film moisture barrier may be engineered and prepared in advance and subsequently laminated to the device or otherwise used to package the device.
To perform efficaciously a moisture barrier must resist the transmission of water or water vapor over a wide range of temperatures. In addition, the layers of an effective moisture barrier must remain laminated to each other. Similarly, the entire barrier must properly adhere to the intended substrate of the engineered device package. Certain known moisture barriers initially provide suitable moisture resistance and adequate adhesion properties but subsequently fail upon long term exposure to heat or moisture. Barrier failure over a length of time is particularly common when the moisture barrier is exposed to damp heat, such as is common if the device is a photovoltaic cell. The embodiments disclosed herein are directed toward overcoming one or more of the problems discussed above.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.